This invention relates to an adapter for providing strain relief to jacketed cables and for preventing moisture or water from damaging the cables. In particular, the invention is directed to a strain relief adapter connectable to the end of a cable conduit, such as a pipe, for securing jacketed cables of variable diameters carrying tip ring wire pairs to telephone junction boxes for distribution to telephone equipment. Further, the strain relief adapter is provided with a sleeve for sealing the adapter from moisture or water.
Telephone lines, which are carried by electrical conductors known as tip ring wire pairs, are generally aggregated at a particular point in a building prior to being distributed and connected to various types of telephone equipment, such as, for example, telephones, fax machines, modems etc. As the tip ring pairs enter the building as part of a multi-conductor cable, the individual tip ring wire pairs must first be broken out from the cable into individual wire pairs. This is normally accomplished in a junction box known as, for example, a building entrance protector (BEP), or network interface unit (NIU).
The multi-conductor cables are generally enclosed in stiff insulation jackets having variable diameters depending upon the particular application. Because these multi-conductor cables carry the tip ring wire pairs that will be connected to various types of telephone equipment, it is necessary to provide strain relief to the cable to insure that the tip ring wire pairs do not become disconnected or loose. Loose or disconnected wires in a junction box can cause serious malfunctions in telephone, computer, or network service requiring costly repair and maintenance service. Moreover, it is desirable to provide a liquid tight seal to prevent moisture or water from invading the adapter and damaging the cable or wires within.
Thus, there is a need for an adapter capable of securing multi-conductor cables of variable diameters and providing a liquid tight seal.
The present invention is directed at overcoming shortcomings in the prior art. The present invention comprises a first nut connectable to an end of a cable conduit such that the cable carried within the conduit can be fed into and through the adapter. A tubular extension extends longitudinally from the base and has a compressible portion for constricting around and, thereby, securing a cable. A second nut is mountable over the tubular extension and has an inner channel provided with a tapered region for constricting the compressible portion of the tubular extension.
The operation of mounting the second nut over the tubular extension causes the tapered region of the second nut to exert a compression force on the compressible portion, which deflects the compressible portion inward. In use, the first nut is connected to a conduit carrying a cable and the cable to be strain relieved is passed through the tubular extension. The second nut is then mounted to the tubular extension to provide strain relief. As the compressible portion is deflected inward an inner surface of the compressible portion contacts the cable and grippingly secures the cable in place. Because the compressible portion can be gradually compressed by the second nut to a desired compression, a range of variable diameter cables can be secured by the present invention. Thus, the need to use cable fastening devices constructed for specific cable diameters is eliminated, thereby improving efficiency and reliability in cable connections.
In a preferred embodiment, the compression portion is comprised of a plurality of deflectable arms having gripping ends. Under a compression force, the gripping ends radially converge and secure the cable.
A second preferred embodiment further comprises a sleeve that is inserted into the tubular extension for providing a liquid tight seal. The sleeve conforms to the inner wall of the tubular extension and is tightly compressed against the cable when the second nut is mounted. Thus, the adapter prevents moisture or water from damaging the cable or the wires within.
Other objects and features of the present invention will become apparent from the following detailed description, considered in conjunction with the accompanying drawing figures. It is to be understood, however, that the drawings, which are not to scale, are designed solely for the purpose of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims.